LiFePO4 DC-DC Charger Placement in 2014 Itasca Sunstar 27N

[Islandguy-WO]

I'm about to start my own conversion to my 2014 Itasca Sunstar 27N. I've already got most of the pieces including a Renogy 50A DC-DC charger. I'm curious to know where other 27N owners that have installed one of these units. I don't have a lot of vacant space so I'm looking for ideas on where to put it.

Also, did you install a Li-BIM as well? I've read some threads here that go back 3 or 4 years where the current BIM ground wire was cut. Sounds like an idea, but thought I'd see if there are any recent ideas.

And if anyone has a diagram or a description of what they've done with their Lithium changeover, I'd love to see it.

TIA,
Bob

 

[powercat_ras]

On my 2015 Vista 27N, I installed a Renogy 40 amp output DC-DC and protective ANL fuses in the front driver's side basement compartment on the back wall near the slideout controllers. I optioned the DC-DC to output 14.5 volts to fully charge the LiFe04 batteries from the DC-DC output, letting the internal BMS in each LiFe04 battery cutoff the charge when it senses battery is fully charged. Or, you may prefer to set the output voltage slightly less if you want the DC-DC output to not charge the LIFe04 batteries to full 100% with BMS cutoff.

Chassis B+ and Coach B+ are conveniently located in the chassis electrical box on the battery disconnect contractors. You also have access to wire KE on the IGN terminal of the Battery Isolation Manager control module which is another connection the DC-DC needs in the chassis electrical box. KE is +12 when IGN switch is in the ON position.

I modified the existing Battery Isolation System Winnebago uses on the Vista 27N to prevent it from connecting the coach and chassis batteries whenever the IGN switch is ON, This modification involves cutting 1 wire, adding a Hopkins dual diode ( sold for double feeding car tail lights when flat towing ), adding a shorrt jumper wire, and making 3 wire splices. I have provided the drawing.

This mod takes advantage of the BIM control module logic that inhibits the coach <> chassis contactor from closing whenever there is voltage present on both the GEN SET and IGN inputs of the module. The mod puts voltage on both inputs whenever the IGN key on +12 volt signal is present.

 

[Islandguy-WO]

On my 2015 Vista 27N, I installed a Renogy 40 amp output DC-DC and protective ANL fuses in the front driver's side basement compartment on the back wall near the slideout controllers. I optioned the DC-DC to output 14.5 volts to fully charge the LiFe04 batteries from the DC-DC output, letting the internal BMS in each LiFe04 battery cutoff the charge when it senses battery is fully charged. Or, you may prefer to set the output voltage slightly less if you want the DC-DC output to not charge the LIFe04 batteries to full 100% with BMS cutoff.

Chassis B+ and Coach B+ are conveniently located in the chassis electrical box on the battery disconnect contractors. You also have access to wire KE on the IGN terminal of the Battery Isolation Manager control module which is another connection the DC-DC needs in the chassis electrical box. KE is +12 when IGN switch is in the ON position.

I modified the existing Battery Isolation System Winnebago uses on the Vista 27N to prevent it from connecting the coach and chassis batteries whenever the IGN switch is ON, This modification involves cutting 1 wire, adding a Hopkins dual diode ( sold for double feeding car tail lights when flat towing ), adding a shorrt jumper wire, and making 3 wire splices. I have provided the drawing.

This mod takes advantage of the BIM control module logic that inhibits the coach <> chassis contactor from closing whenever there is voltage present on both the GEN SET and IGN inputs of the module. The mod puts voltage on both inputs whenever the IGN key on +12 volt signal is present.

Thanks for the very detailed description of what you to your 27N. I printed it out and added it to my file. Hopefully I'll get started on my conversion this week. Any chance on seeing the whole image of your diagram? The sides appear chopped off. I'm very interested in seeing the whole image.
Bob

 

[powercat_ras]

Here you go, I created this to document my owner modifications to the DC systems of the 2015 27N and also to help me understand how the coach and chassis disconnect switches worked. Note there is a second modification of the addition of an anti-theft switch mounted in an empty space in the circuit breaker panel in the locked chassis electrical box. You can disconnect the chassis battery then unlock and open the chassis electrical box and and throw the anti-theft switch and this disables the chassis battery switch from reconnecting the chassis battery, preventing the coach from being started or driven until the anti-theft switch is thrown back to the normal position.

 

[Islandguy-WO]

Wow! That's quite the diagram! Way beyond my level, but I'll have fun looking at it. Thanks for posting it.
Bob

 

[klook]

That is a wonderful and well laid out schematic. Thanks for sharing. What did you use to create it?

 

[EverettO]

Does your rig have the chassis and coach batteries located under the step? I have a 2008 Itasca Sunova 26P. I just located all the batteries (1 lead acid chassis battery and 2 LIfepo coach batteries in their original locations under the step and added the MPPT there too. I did NOT add the LiBIM both because installation would have been a bear and because I read this is not really needed for 2 or 3 battery units. This is per the mfg of the LiBIM (Battleborne?). Apparently 2-3 batteries will not draw enough for it it to be needed. That simplified my project greatly. Now a year later, no problems. And this is for a 375 panel on the roof. Have fun!

 

[klook]

I think the mppt is not weatherproof? Maybe some are? Lead acid is required to be in a vented or open compartment so.......

 

[MikeyC-WO]

I added a Temco 300ah lifepo4 for coach and an lifepo4 Ionic 1400ca start chassis battery each battery has bms and built in heat. I have the victron 50 amp dc-dc charger I stalled in same area as the BIM tapped off bim to power the dc2dc in line and used the ignition line sense to enable the victron to begin charging. Since everything is lifepo4 nothing else special needed and I retain full functionality with if I need to use the temporary coach to chassis together. The alternator never sees the full load so it’s protected. Working great. What makes it complicated for many is using a lead acid chassis and lifepo4 coach. Dump the lead acid chassis your world will be better. Note though.
The chassis start ionic has a sleep mode so I learned after coach sits a while to use the app on the phone to wake up the chassis before starting. Good luck
Sunstar LX 35F

 

[Islandguy-WO]

Does your rig have the chassis and coach batteries located under the step? I have a 2008 Itasca Sunova 26P. I just located all the batteries (1 lead acid chassis battery and 2 LIfepo coach batteries in their original locations under the step and added the MPPT there too. I did NOT add the LiBIM both because installation would have been a bear and because I read this is not really needed for 2 or 3 battery units. This is per the mfg of the LiBIM (Battleborne?). Apparently 2-3 batteries will not draw enough for it it to be needed. That simplified my project greatly. Now a year later, no problems. And this is for a 375 panel on the roof. Have fun!

Yes, I'm the same. My plan is to put the LiFePO4 battery there as well. But I don't have room for the DC-DC charger. I'm also inclined to not change the BIM. So far I have installed roof top solar. Since I live on the coast of British Columbia, just about all the campgrounds are under trees so I've gone with two 200 watt portable units.

 

[Islandguy-WO]

I added a Temco 300ah lifepo4 for coach and an lifepo4 Ionic 1400ca start chassis battery each battery has bms and built in heat. I have the victron 50 amp dc-dc charger I stalled in same area as the BIM tapped off bim to power the dc2dc in line and used the ignition line sense to enable the victron to begin charging. Since everything is

I've gone with a Wattcycle 280ah which fits in the same footprint as my two 6v golfcart batteries. I've recently read that there are Iifepo4 start batteries now. When it comes time to replace mine, I will have a look at them. My BIM is not easily accessible. It's hidden away behind a narrow wall of circuit breakers. I'll likely install it in one of the two forward storage compartments wherever I can make room for it.

 

[EverettO]

I think the mppt is not weatherproof? Maybe some are? Lead acid is required to be in a vented or open compartment so.......

Thank you! Yes the battery compartment is vented below through the bottom of the rig. I had not considered that this may not be a good place for the MPPT. So far we are fine but it may not remain that way! I may need to relocate that. The previous owner had one installed behind the TV in the bedroom. Now I know why!

 

[MikeyC-WO]

I've gone with a Wattcycle 280ah which fits in the same footprint as my two 6v golfcart batteries. I've recently read that there are Iifepo4 start batteries now. When it comes time to replace mine, I will have a look at them. My BIM is not easily accessible. It's hidden away behind a narrow wall of circuit breakers. I'll likely install it in one of the two forward storage compartments wherever I can make room for it.

My BiM was behind the same two screws and drop the breakers down access to BiM is there but I just loosened a nut or two and put the victron in between works great. I see with Bluetooth the victron limits the load on the alternator and hold the load for 50amp to the coach batteries the alternator puts enough voltage on the lifepo4 start to keep it happy and topped off.

 

[powercat_ras]

That is a wonderful and well laid out schematic. Thanks for sharing. What did you use to create it?

Microsoft Visio